Field of the Invention
The present invention relates to a hand lamp which is powered electrically by a low-voltage battery, such as a vehicle battery, and which is of the kind defined in the hand lamp powered by a low-voltage battery.
A hand lamp of this kind will include an electric cable that has a fluorescent tube fitting at one end thereof, a battery connector means connected to the other end thereof, the cable including two conductors which are each provided with connector means for detachable connection to a respective terminal of the battery, and further includes fluorescent tube lamp, and an electronic HF lamp ignition means.
A hand lamp of this kind has the advantage of providing a high light yield or luminous efficiency in relation to energy consumption.
It is important to be able to minimize the energy consumed by a lamp in relation to a given luminous flux, particularly in the case of water-going vessels, such as motorboats, yachts, and also with respect to cars and the like, which, in practice, carry only a single source of current in the form of a low voltage battery (12 volt accumulator). In order to enable the light sources to be used comfortably, it will preferably be connected to the battery by means of a long cable that will allow the light source to be moved to a position located at a relatively long distance, from the battery.
It is known to use to this end a hand lamp whose light source consists of a low-energy bulb, for instance a halogen bulb of good efficiency that can be operated on battery voltage. However, as a result of the requisite length of the hand lamp, the power losses in the cable become problematic.
These losses can be alleviated by using heavy gauge cable conductors, although this renders the cable expensive and difficult to handle. It is also known to use a light source in the form of a compact fluorescent tube and to energize the tube with the aid of an ignition means fitted at each end of the cable. If the converter is placed at the battery end of the cable, the cable conductors will transmit high frequency noise, owing to the fact that the ignition means, or igniter, includes a high frequency converter. This means that at latest the cable must be screened along the whole of its length, causing the cable to become relatively heavy, clumsy and expensive. If the HF device is, instead, place in the proximity of the light source, the power loss in the cable will become problematic unless the cable conductors are given a heavy gauge, although this will again result in a cable which is heavy, difficult to handle and above all, expensive. The HF device located in the proximity of the light source will, of course, also generate a high frequency disturbance.